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Clay - Need help from the soil experts

Posted by ricksample 6 (My Page) on
Sun, Mar 16, 14 at 17:28

Last year I cleared off 2 acres of land at the end of my property. After hard rains it would drain quick. I would dig holes in multiple spots, dump water and it would drain pretty quick. I was pretty happy with this newly found 2 acres of good soil... it didn't show it's true form until winter showed up. I don't know if it's the extreme wet weather we've had this year or what... but here is what I found.

A week ago the snow melted and it's been 45 for the high ever since with no precip. I figured the ground should be solid back on this 2 acres. I stepped foot on the ground and it's like a sponge. I didn't know what to think so I got my shovel out. I scooped the top 2-3" off and it was very wet. Then I dug my 2' hole. This soil seems moderately dry for some reason. It's clay, but not to bad. The color is a dark brown. After a short while you can see water start to seep in from the cracks in this hole. So it fills the hole.

On this 2 acres, I'm planning to plant a bunch of beds with trees and other plants. In between the beds will be 15 foot grassy paths that you can walk along. So essentially the entire 2 acres will be planted with mulch beds except for the grassy paths.

Do I buy topsoil/compost and work it in with a rototiller little by little? These rototillers are expensive at $700 plus the cost of the topsoil/compost. I could hire someone to rototill it in, but I plan to do it sections by sections and they would probably have to make 20+ trips to my house if I can find someone to do it.

Or is it possible just to put 6-8" of topsoil/compost where my beds are going, plant the trees/flowers, then top off with another 2-3" of mulch? So this would create a lot of raised beds that would be raised around 10".

I'm hoping the second one would be best, just because I think it would look nicer to have a bunch of beds that are raised higher than the grassy pathways. My main concern with this is that I don't want the water to run quick through the new topsoil/compost/mulch and be trapped between the good/clay soil.


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RE: Clay - Need help from the soil experts

Some background information about your land would be helpful.....Was this land in trees, pasture, row crops, or brush/weeds before your clearing. In other words, is similar land in your area useful for crops? Is it level, rolling, or sloped?

Few soils are just clay. Mostly they are clay loam, silt loam, sandy loam, sandy, and such. This time of year it is common to have soggy soils in northern areas. Most will dry out some shortly. It is possible though that you need tile ditching.

If your soil is unfertile, Adding good topsoil with mulches will speed up the process. If your soil is halfway decent, I suggest working any additions into the existing soil and avoid a sharp deliniation of soils, but rather have a deeper soil.


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RE: Clay - Need help from the soil experts

Thanks... it was tall very thick brush & it's level. I do have a few neighbors that plant crops in there fields. It's not solid clay... I have a patch behind my house that's about a 10x10 section that's solid blue/gray clay. The color of this soil is dark brown.

What I don't understand is that my front yard is almost the same way. I could step on my front lawn and you can hear the water sound, but it felt solid you couldn't see the soil move. Then after a couple days the water drained and today you could easily plant in the front

The back field that I cleared doesn't have the solid feel that the front yard has. When you step on the grass in spots you can see the patch of grass sink/slide a little. When saturated you can pull on the grass in the front yard and it would tear the grass apart. If you pulled on the grass in the field it'll literally lift the grass, roots, and a little soil out of the ground leaving you with bare soil. But I physically see very little water. You scoop the top inch or two off the top that's gooey with grass roots, everything underneath is moderately dry.

If the yard is overly saturated because of the bad winter, I would think the front yard would also be this way. I didn't have any problem with this field during the summer though. It rained and would drain rather quick. Even filling holes with water would drain quick. Now it seems the top layer of soil is holding the water.

I wasn't sure if I should just plant everything very high, amend the soil with compost/top soil or create all the beds raised with new topsoil. This is a big project where I'm planting 50+ trees, I just don't want to take the chance and have them get to water logged. Especially since every bed will be covered in mulch which will cause the water not to evaporate or be absorbed by the grass. I fear that if I do nothing and add mulch, water could sit here permanently and kill whatever is left of the microorganisms.


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RE: Clay - Need help from the soil experts

Also, what got me confused was reading the comments from the post below here on gardenweb. How multiple people are saying to toss the soil on top of the clayish yard and as the roots penetrate and the other organisms come, the compost/top soil will eventually work itself down into the native soil. Makes sense in theory, but I'm not sure if it'll work in reality.

They also went on to say your tiller can only get down so far, if it rains this area you tilled will fill up like a bathtub .

Then on other sites I also found counter arguments saying the soil must be amended otherwise water will sit between the two layers. I've also read that you must not amend or add top soil at all to beds to which you're planting trees which is what I'm planting. It's very confusing non-the-less.

Here is a link that might be useful: Link

This post was edited by ricksample on Sun, Mar 16, 14 at 19:40


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RE: Clay - Need help from the soil experts

The primary mineral component of your soil is clay, although you probably have some sand and maybe some silt particles as well. "Topsoil" will be about 95 percent of the mineral component of soil, or more of what you already have when what that soil needs is organic matter. To learn more about the soil that is there use these simple soil tests,
1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drains’ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell.

5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.


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RE: Clay - Need help from the soil experts

The soil in my area is almost solid clay.

We have found through bitter experience that clay soil should not be worked or even walked on that much when it is wet. If it is, the air holes will be eliminated, and when it dries out it will be bricklike. In heavy soil like this, it is also a major task to mix in amendments, which is another reason why some of us give up and leave it to the elements to do the work for us.

We have planted several trees in our soil that have done well, though--but imo you need to find trees that like clay soil for best results. Years ago in our neighborhood oaks not suited to this area were planted all along the streets. They have grown to be monsters, but every so often one will fall, the roots almost totally rotted away. Oak trees can easily take out a house; their wood is extremely heavy.

Additionally, some trees form much deeper roots than others, and this may help to determine what you need to do with your soil. Since you have been getting conflicting input on here, you might want to give your agricultural extension service a call to see what works best in your area, boith in terms of soil preparation and best tree species and varieties.

I have had a good deal of success with the "lasagnia" garden technique for vegetables, but trees are a different matter, especially with the major project you are planning.

You might find white clover to be a soil amendment help. I recently read that one variety forms 40 inch taproots that die after the first winter, leaving holes that water can penetrate.

[Is your planting going to be in a residential area? As you probably are aware, some trees are more prone to shedding large branches and are best not planted too near structures. I have a tulip poplar that I have surrounded with shrubs for that reason.]


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RE: Clay - Need help from the soil experts

I have soil with a high clay content. I live on a long, 2 mile slope thats heavily irrigated, so the water eventually works its way underground down to my place and in August, I have seeps all around the garden.

I tried several techniques, including rototilling in organic matter and so on, but ended up with a heaped soil raised bed system as the best alternative. I haven't used the rototiller in years. The worms do all the work of incorporating organic matter down into the deeper soil layers.

IOW, I'd go with your simplest solution,

….. just to put 6-8" of topsoil/compost where my beds are going, plant the trees/flowers, then top off with another 2-3" of mulch? So this would create a lot of raised beds that would be raised around 10".

and spend the rototiller money on something else. I mulch heavily with grass clippings and compost, and the worms love it.


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RE: Clay - Need help from the soil experts

Could your ground still be frozen ?
If it is, the water from melting snow would saturate the top soil and create what is called a bathtub effect because the water can't drain past the frost.
Just a thought.


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RE: Clay - Need help from the soil experts

If you had heavy clay soil , you would know it because it is very sticky and holds together like glue. You might have combination soil.
I would ask someone to look at my soil before I invested that much effort and planted that many trees. The place where you are buying the trees probably has a consultant that would do it for free. It would be worth your while before you waste you time and money.


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RE: Clay - Need help from the soil experts

After reading the posts I had the same thought as Darth that your subsoil is frozen. Here in southern Wisconsin frost levels reached 8 ft or more. I am assuming you are z6 and I am z4-5 and we will not be seeing thawed ground for a month or more so drainage will be affected. Wis has flood alerts all over due to the soil being frozen and if your plot is very level is might just be pooling in the top few inches FWIW.


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RE: Clay - Need help from the soil experts

I live in the Mississippi river delta, so clay and river silt are all the soil we have. I've gained quite a bit of first hand experience.

If you have heavy clay, the easiest way to deal with it is to put down a thick layer of compost/organic matter and let it decompose on top. You will find that over the course of one year the clay underneath will become much more workable with no other effort. After a couple of years of this, it's just night and day the difference it makes.

Now days, if I want to start a new bed, I'll pile up organic matter for a couple of years to loosen things up and just put annuals in it while the organic matter is doing it's thing. (I'm fond of rooting my own coleus in place for this purpose) After two seasons of that, you can easily get out the tiller and work it in deep with much, much less effort than you would have exerted before your clay was transformed.

Even if you don't ever bother to till anything in, the transformation is quite astonishing, it just takes a bit longer to work in deeper.

Really, if there is anything experience has taught me it's that you don't have to worry about fixing everything right this second, and that time really is on your side.

The only thing I avoid is doing permanent plantings of anything that will not be happy with me piling on organic matter deep for those first couple of years.


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RE: Clay - Need help from the soil experts

  • Posted by glib 5.5 (My Page) on
    Tue, Mar 18, 14 at 17:08

I am with Darth and wisbill, when I read the OP it was clear to me right away. Zone 6a here, and the subsoil is still quite frozen. Maybe tomorrow, when we get half a inch of rain, in those spots that are clear of snow. Where we have snow, it may be another week.


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RE: Clay - Need help from the soil experts

A lot of good information in this post... thanks everyone!

Kimmsr - Thanks, here are the answers to your question:
1. I did a couple soil tests, it came out 0% sand, 99% silt, 1% clay.
2. I can do the drain test at the moment, the holes fill up with water themselves.
3. The soil doesn't fall apart, you can poke your finger through the soil. But it does crack very easy while doing this.
4. The soil smells great, very earth smell
5. I did a couple different shovel scoops. Each one had around 2 worms

Let me know what you think I should do, if anything. I'm concerned because I have a bed where I didn't do anything to the soil. I planted then mulched. This soil spot is heavy clay, but was workable a few years ago. Today that soil is unworkable. I'm actually going to dig this bed up and put grass down. Under this mulch smells terrible from where water sits 24x7, even in the summer. I think this soil became this way because I removed all the grass which had very deep roots and replaced it with mulch which kept the water from evaporating. This soil back in my field isn't clay, but I'm afraid it may become worse if I add mulch and kill the grass.


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RE: Clay - Need help from the soil experts

David52 & Billums - Just putting organic matter on top will improve the soil underneath? I haven't heard of this... just about every article or video I watch said that you have to work it into the soil for it to be effective.

I definitely decided not to till the entire field. Then I would have to replant the grass and everything else. I'm thinking about working just the beds. I have two options:
1.Tilling in the organic matter, plant, then mulch.
2. Plant everything in this bed very high with a large slope so water runs away from the plant, fill all the beds with a couple inches of organic matter, then mulch without tilling.

Will doing any of these things create a "bathtub" effect? It would be nice not having to till up the entire bed, but if it'll make a huge difference I wouldn't mind the extra work.

Unfortunately I can't wait for the organic matter to improve the soil before planting because I have all 40-50 trees here at my house from mail order. So I have to try to figure out how to improve the soil and plant all in one step.


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RE: Clay - Need help from the soil experts

Glib - I'm not sure... I have parts of my soil (in front of my house where it gets no sun) still completely frozen. But I dug a few samples and brought the soil inside. I can't physically see any ice or frost in the samples. I took a piece of soil about 1 foot square. Then I sat it on the counter and pushed down on the top. I watched as the water left the soil and went over my hand. Then I tore the sample apart and couldn't find anything or what was causing the top layer to hold the water. Unless the cold is causing the soil to compact more for some reason.


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RE: Clay - Need help from the soil experts

If the holes you dig fill up almost as soon as you dig them you may have a high water table. That may be a seasonal thing or it may be year around so you may need to build raised beds for anything other than grass. Adding organic matter will, over time, improve the drainage some depending on how high the water table is during the summer. A neighbor, who's property is 5 feet lower then mine, dug two ponds that are full of water year around because the high water table keeps them full, about 6 inches below the rest of the property.
What did the test show about organic matter?


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RE: Clay - Need help from the soil experts

The key to this thread is in your first post where you stated that last year the soil drained quick and looked good. You had the soil test done and should have gotten any suggestions on what it may need. Obviously compost will help along with any other amendments. I would wait 2-4 weeks and check again if you still have concerns, call a landscaper or someone with formal knowledge of the trees you wish to plant for advice. If you are going to make a large investment in your land with 50+ trees my advice is to slow down and talk with people that do it for a living. Any quality landscaper will give a 1-or 2 year warranty on trees so they know what works in your area.


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RE: Clay - Need help from the soil experts

Kimmsr - It had a little organic matter... not much. Just a few small things floating on top. Here's the picture. Now that I look at the picture better, it looks like the bottom 3/4 of the soil is silt, the top 1/4 is clay & no sand.

Wisbill - I did get a lot of great information. One small thing I did run into after calling several companies about compost is that they don't take their trucks off the driveway until July/August when the soil is hard which is understandable.

I think what would be best for the moment is to plant all the trees that I have here at my house and plant them high. At least 5" above the soil on a large sloped mound 4 to 5 feet diameter. Then watch as it as it rains all spring/summer to see how fast the soil drains. If it drains fairly quick for the next several months, I'll still buy the compost and add 2-3" to each bed in August before I mulch. If it doesn't drain good, I'll added compost to the bed and till it in before I mulch. The only downside is that I won't get any compost under or in the soil that's next to the plant. I think this may be my only option because I really don't want waste a spring not planting


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RE: Clay - Need help from the soil experts

Sand, the largest and heaviest of the mineral particles, will always be on the bottom followed by silt with clay above that and any organic matter floating on top of the water. It is difficult to tell from the picture what your soil is composed of, but there is no organic matter and that is telling you what you need to do, add organic matter.
No matter what you have for soil it needs organic matter in adequate amounts. I have found that 6 to 8 percent works very well and is sustainable.


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RE: Clay - Need help from the soil experts

Thanks everyone... you all seem very knowledgeable. I haven't been able to do much or get the soil test. We got an inch of rain this past weekend followed by a few inches of snow. Which created a mess in the field. I don't know which direction I need to head... I almost came very close to putting my place up for sale just because I spend a huge amount of time gardening and can't do any gardening until it's 100+ degrees outside in the middle of summer thanks to the heavy silt/clay.

I definitely don't want to till.. The main reason for this is that I would have to till and do all this work when the temps are 100+ during summer when the land is completely dry.

I'm reading a lot of conflicting information. Some say you must till others say don't bother let mother nature do it. Well I just seen another post on here of someone saying their new soil didn't mix with the native soil after 3 years, Some are telling me to create a lot of raised beds with new soil. Some say just add compost once a year, others say you must add it every year.

I'm trying to think about this logically... just by what I see from walking around my property. I have a few small hills... these hills are also heavy silt/clay, but it's raised higher and it doesn't have the spongy feeling of the lower soil. What if I tried to recreate this? I don't care if my grassy pathways get real wet.... my goal is to keep my actual beds dry.

I need to mix the soil somewhat... but I don't want to till. Would it be bad if I lightly turned the soil over in each bed with a shovel? I have an unlimited supply of brush/dead tree limbs/logs/sticks. Next pile a thin later of these on the turned soil to add pure organic matter. Then add compost/topsoil. The topsoil/compost I found and really like is a mixture of raw topsoil, sand and 25% leaf compost for $25/yard. After that, add 2-3" of mulch.

Turning the soil over seems like it would help mix the two somewhat to get the process started. In the end, the topsoil/compost will add about 6" in height with another 3" of mulch... the total height of each bed would be aprox 9" above ground.

The concerns I have doing it this way are:
1. Will the sand in the new soil clog what little air space I have in the native soil?
2. Will water become trapped when it gets below the turned soil?
3. I've never bought topsoil before... will this fluffy stuff become hard & compacted enough to support 40' tall trees? I'm hoping this new soil/tree limbs/compost will improve the soil below so the trees can grow deep... but I've also read that trees have most roots in the upper 6-12" of soil

Here's my plan so you can get a better understanding of the beds. That space is around 300' wide x 300' deep. The colored icons in each bed are different types of trees... mostly conifers. Each bed is roughly 2000 SQFeet... so I would need a lot of compost/topsoil. I'm not going to kill myself so I would just do 1 or 2 beds a year lol.

This post was edited by ricksample on Mon, Mar 31, 14 at 8:39


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RE: Clay - Need help from the soil experts

Sand is the largest of the mineral soil particles and soils of sand have large pore spaces that allow air, water, and nutrients to flow through that soil pretty much unimpeded.
Add Silt, smaller than sand, and Clay, even smaller, and the pore spaces are filled in somewhat slowing the movement of all three. Clay soils tend to hold onto both nutrients and moisture and do not easily transfer them to plants, but adding organic matter to any soil will help by holding both nutrients and moisture in Sand and creating conditions that cause them to be released in Clay soils.
"Topsoil" is defined as the top 4 to 6 inches of soil that might contain some organic matter. The term "topsoil" is meaningless since it is the seller that determines what it is and I have seen spent foundry sand sold as "topsoil".
If you are to spend money on soil look for some that contains a minimum of 5 percent, preferably 6 to 8 percent, organic matter, and forget labels. A really good soil, loam, will be about 45 percent sand, 25 percent silt, 25 percent clay, and 5 percent organic matter.


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RE: Clay - Need help from the soil experts

Thanks Kimmsr - This topsoil appears to be good. They custom mix it with sand & leaf compost. I want to create these beds raised, but I also wanted to incorporate a lot of organic materials. I'm trying to kill 2 birds with 1 stone. I don't want to add pure organic matter because I would like these beds raised and OM would decompose quick. But I didn't want straight topsoil which could be mostly what I already have. That's when I found this custom blended stuff.

I was researching a term called hugelkultur... where people bury logs and large sticks. I have an ample supply of huge logs/sticks/paper that I can put under this new topsoil/compost that I think would make the soil better in the future. I think it would add more organic material than just top dressing with leaf compost. With the logs/sticks/leaf compost/paper I'll more than likely have at least 30% OM and the rest would be topsoil which would be a combination of raw topsoil screened with added sand.


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RE: Clay - Need help from the soil experts

Placing organic matter atop works. It's not so much the organic matter that works the soil but all the biology feeding on the organic material that works the soil. I have heavy clay soil with much sand and silt. However, the water/moisture issue is different. In warm weather I must moisten the soil even occasionally after placing the organic matter atop the area to be treated because we are dry. I cover with organic material to please the worms, grubs and soil life forms. I'll even add molasses or drench with worm tea. Then I cover it with an organic mulch the biology favors. Hay, especially, alfalfa works well. Within one week I can take a shovel to the first six to eight inches. Hardy plant life beneath this flourishes in that week, too. It's almost magical. Then, I work more organic material directly into the soil. Mulch, again. Keep moist. The mulch usually does a great job of retaining the moisture at this point. Another week passes and a deeper depth is easier to obtain. Once I can double dig the area easily I begin routine garden-bed preparations. The previous organic material, in my soil, is usually spent by the biology that just worked the soil and needs replenished for the desired plants.

I add this for those who might have back problems and are needing a way to process heavy clay in an easier fashion.

Because my area is dry and in continual drought H-Kulture has been so blessed in my garden. I have volunteer kale that is in its 5th season. Everything my clay soil cannot do is remedied by h-kulture. In our dry season it acts as a swale capturing water and slowly releasing it into the earth. In winter plant roots stay warmer in our harsh colds. for this reason in my area kale does not go to seed on my h-kulture. Their roots don't get cold to trigger the process. Volunteers in spring are prolific. It's labor intensive to build, but you're done for a long time afterward.


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